ksack001

210 Silverado 1500, 5.3. Ok so recently my truck has been idling very low on cold start. It’s supposed to idle at like 1500 or so then drop down as the engine warms. For about 2 weeks now when doing a cold start after sitting all night it idles only at 500 the normal idle speed. If it sits for only 5-6 hours and I start it, it has the high idle like it’s supposed to then drops back down when warm, but when sitting all night it starts up fine but there’s no high idle until warm like it’s supposed to. There are no codes at all and my MPG are way down. Only thing done to the truck is a Carven Cat back, Range Device which has been there a while, new battery and KandN filter. I’m at a loss here. I’ve changed the ECT, and have unplugged battery to reset ECM, but nothing. I have a new MAF sensor coming but I’ve cleaned the current one. Any ideas?

There are no codes at all. I unplugged the battery for 10 min and plugged it back in we will see in the AM.

Yeah it def jumps up on cold starts and works it’s way down as it wants up, not sure of exact idle speed but it’s not doing that at all anymore. On cold start it’s idling at normal idle speed after sitting all night.

With range unplugged I have the same issue. I wouldn’t think the range would do anything to cold start idle speed. The range has been plugged in for a month. Just started having problems 4 days ago. MAF is clean, just checked. This is weird

2015 Silverado 1500. 1 month ago I put a carven catback, range AFM disabler and a KN air filter, there are no other mods to this truck. 4 days ago on cold start I noticed it doesn’t idle high and then come down when engine is cold, it’s starts like it’s been running all day but hasn’t. Truck sat all night last night started this morning still no high idle just started like it had been running all day. There are no engine lights on. What in the world could be causing this?

Starter replaced today and noise is resolved.

That’s what I’m thinking. I’ll replace the starter and see what happens.

There’s the video taken right at the starter.

It only happens during crack once engine is cranked over it’s not there. Not when engine is running only during cranking over. Doubtful it’s the water pump.

Did you ever figure out what this is? I have a 15 silverado and it’s doing the same thing. A chirp on startup cold or hot and only at start up.